11.beta.-Hydroxy-3,20-diketopregnenes having a cyclic 16,17-acetal or ketal group are well known and widely used anti-inflammatory agents. Exemplary of this type of steroid are halcinonide (21-chloro-9-fluoro-11.beta.-hydroxy-2',2'-dimethylpregn-4-eno[16.alpha.,1 7-d][1,3]dioxolane-3,20-dione) and triamcinolone acetonide (9-fluoro-11.beta.,21-dihydroxy-2',2'-dimethylpregna-1,4-dieno [16.alpha.,17-d][1,3]dioxolane-3,20-dione). The limited solubility of these pregnenes in slighty polar solvents such as ether leads to problems in formulation design.
In order to ease the problems of formulating 11.beta.-hydroxy-3,20-diketopregnenes having a 16,17-cyclic acetal or ketal group (and in order to prepare new and useful anti-inflammatory agents), the prior art has prepared 11-keto and 11-acyloxy steroids. While these modifications do increase the solubility of the steroids, they generally result in steroids of lesser activity.
The prior art also shows that some steroids having 11-acetal groups have been prepared. For example, Fukushima et al., J. Org. Chem., 26, 520 (1961) disclose the formation of 11.beta.-(methoxymethyl)-17,20;20,21-bismethylenedioxypregn-4-ene-3-one as a by-product during the reaction of hydrocortisone with formaldehyde. Gardi et al., J. Org. Chem., 27, 668 (1962) and Tetrahedron, 21, 179 (1965), disclose steroids having 17,21-cyclic acetal groups as substituents and in the 11-position a group of the formula ##STR1## wherein R is alkyl or aryl.